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Uncommon exoplanet 23 EP

BD-210397 b

RA 33.3024° · Dec -21.1962° · exoplanet

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Score breakdown

· 4 badges
23 pts · Uncommon
Uncommon 34 pts → Rare
  • Frozen world +8
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 23

11 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Frozen world · +8
  • Multi-planet system · +6

Trivia

What makes it special

  • Frozen world. A deep-frozen world, too far from its star's warmth for anything to stay liquid.

Hard to believe

  • It would float. It is less dense than water. Drop it in a big enough ocean and the whole world would bob on the surface.

What it actually is

  • What it is made of. Lighter than Neptune — a puffed-up ball of hydrogen and helium with no surface anywhere on it to stand on.
  • Crowded system. One of at least 2 planets orbiting its star.

Sense of scale

  • In perspective. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 9.8 you'll want a small backyard telescope.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around October — that's when to go looking.

Properties

density gcc
0.429
diameter km
178586.8
discovery facility
La Silla Observatory
discovery method
Radial Velocity
discovery year
2023
dist ly
77.4046
eccentricity
0.1
eq temp k
104.11
host star teff
4051
insolation
0.02
mag
9.84
mass earth
214
name
BD-210397 b
orbital period days
1891
radius earth
14
semi major au
2.63
spect
K7 V
sys num planets
2
sys num stars
1

About BD-210397 b

BD-210397 b is an uncommon exoplanet. It lies about 77.4 light-years from Earth, shines at apparent magnitude 9.84, has spectral type K7 V and has an equilibrium temperature near 104 K.

A deep-frozen world, too far from its star's warmth for anything to stay liquid.

How to see it

At apparent magnitude 9.84, a small backyard telescope will bring it into view.

Like any astronomical target, BD-210397 b is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why BD-210397 b is an uncommon exoplanet

BD-210397 b scores 23 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 11 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Gas giant, Frozen world and Multi-planet system — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.